81,835 research outputs found

    Ionospheric Corrections via PIM and Real-Time Data

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    We describe a method for removing ionospheric effects from single-frequency radio data a posteriori. This method is based on a theoretical climatological model developed by the USAF, which returns electron density as a function of position and time along the line of sight to the source. Together with a model of the earth's magnetic field, ionospheric delays and Faraday rotation values ensue. If contemoraneous ionospheric data -- GPS TEC observations or ionosonde profiles -- exist, they can be incorporated to update the modeled electron densities.Comment: 6 pages, 2 fiugres; LaTeX2e (96/12/01); uses elsart.cls (2.15, 98/07/15); to appear in New Astronomy Review

    MCFM for the Tevatron and the LHC

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    A summary is given of the current status of the next-to-leading order (NLO) parton-level integrator MCFM. Some details are given about the Higgs + 2-jet process and the production and decay of ttˉt \bar{t}, both of which have recently been added to the code. Using MCFM, comparisons between the Tevatron running at s=2\sqrt{s}=2~TeV and the LHC running at s=7\sqrt{s}=7~TeV are made for standard model process including the production of Higgs bosons. The case for running the Tevatron until 16fb1^{-1} are accumulated by both detectors is sketched.Comment: Talk presented by R.K Ellis at Loops and Legs in Quantum Field Theory 2010, Woerlitz, Germany, April 25-30, 2010, (6 pages and 4 figures

    Inflation and personal saving: an update

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    Inflation (Finance) ; Saving and investment

    Hadronic production of a Higgs boson and two jets at next-to-leading order

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    We perform an update of the next-to-leading order calculation of the rate for Higgs boson production in association with two jets. Our new calculation incorporates the full analytic result for the one-loop virtual amplitude. This new theoretical information allows us to construct a code including the decay of the Higgs boson without incurring a prohibitive penalty in computer running time. Results are presented for the Tevatron, where implications for the Higgs search are sketched, and also for a range of scenarios at the LHC.Comment: 16 pages, 4 figure

    QCD corrections to the hadronic production of a heavy quark pair and a W-boson including decay correlations

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    We perform an analytic calculation of the one-loop amplitude for the W-boson mediated process 0 \to d u-bar Q Q-bar l-bar l, retaining the mass for the quark Q. The momentum of each of the massive quarks is expressed as the sum of two massless momenta and the corresponding heavy quark spinor is expressed as a sum of two massless spinors. Using a special choice for the heavy quark spinors we obtain analytic expressions for the one-loop amplitudes which are amenable to fast numerical evaluation. The full next-to-leading order (NLO) calculation of hadron+hadron \to W(\to e nu) b b-bar with massive b-quarks is included in the program MCFM. A comparison is performed with previous published work.Comment: 45 pages, 17 figure

    The latent process decomposition of cDNA microarray data sets

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    We present a new computational technique (a software implementation, data sets, and supplementary information are available at http://www.enm.bris.ac.uk/lpd/) which enables the probabilistic analysis of cDNA microarray data and we demonstrate its effectiveness in identifying features of biomedical importance. A hierarchical Bayesian model, called latent process decomposition (LPD), is introduced in which each sample in the data set is represented as a combinatorial mixture over a finite set of latent processes, which are expected to correspond to biological processes. Parameters in the model are estimated using efficient variational methods. This type of probabilistic model is most appropriate for the interpretation of measurement data generated by cDNA microarray technology. For determining informative substructure in such data sets, the proposed model has several important advantages over the standard use of dendrograms. First, the ability to objectively assess the optimal number of sample clusters. Second, the ability to represent samples and gene expression levels using a common set of latent variables (dendrograms cluster samples and gene expression values separately which amounts to two distinct reduced space representations). Third, in contrast to standard cluster models, observations are not assigned to a single cluster and, thus, for example, gene expression levels are modeled via combinations of the latent processes identified by the algorithm. We show this new method compares favorably with alternative cluster analysis methods. To illustrate its potential, we apply the proposed technique to several microarray data sets for cancer. For these data sets it successfully decomposes the data into known subtypes and indicates possible further taxonomic subdivision in addition to highlighting, in a wholly unsupervised manner, the importance of certain genes which are known to be medically significant. To illustrate its wider applicability, we also illustrate its performance on a microarray data set for yeast

    Activities of the RTG Radiation Test Laboratory Progress report, 1 Jul. - 31 Dec. 1969

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    Safety, gamma ray spectrum, and data analysis of SNAP fuel capsule
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